I've had exactly this problem this week, on an S3-391 that I bought 12 days ago - suddenly started happening out of nowhere a couple of days ago. The only change in the environment that could have any bearing on the issue - to myk knowledge - is that I switched to a new USB wireless mouse the day the issue started appearing - I note others have suggested that there could be a conflict with USB devices. I've been running the 225 driver since the day I got it and let Windows update pick it up. Between then and the day the problems started I've downloaded GBs of stuff, mostly through synching all my stuff back from Dropbox, Skydrive and Evernote.
So: I wasted about three hours yesterday trying to resolve the issue. Spoke to the retailer and had extensive chat session with Acer Support, both of whom were sane and helpful, particularly the retailer, SaveOnLaptops, who even advised me to log the issue with Acer within 14 days of purchase otherwise they would not class it as DOA and it would be a little trickier to get my money back (although, frankly, the UK Sale of Goods Act gives me a lot of protection anyway).
The best Acer could offer was 'We have some new drivers - the 225 version'. When I told them I was already running this version, next step was 'We advise you do a full system restore', which I declined. I've tried reverting to 217 and some older 9 series drivers I found somewhere. I've tried these combinations as a 'standard' install and with a complete purge of the existing driver set (removing them from the adapter settings if necessary. No fun in a machine with no other means of connecting to the network!
Have I resolved it? I think so - by installing the 10.0.0.255 drivers referenced earlier in the thread. I too found the only way I could get hold of them was to install DriverMax and let it find them - they just don't appear to be available anywhere else, so I'd love to know where DriverMax source them from! I had to try a couple of times with the install, fully purging the old drivers from the adapter settings the second time as DriverMax does all the installs from its proprietary interface. Second time round, it appears to have worked - suddenly I'm back to decent throughput and no drops in the last 12 hours. Suggest anyone suffering try this resolution - I almost didn't, assuming that the reference to 255 earlier in the thread was a typo for 225, given than Googling it turned up nothing...
I note the Acer support Driver download site still has 10.0.0.225 which is useless.
United States